Unmanned robotic vehicles can be deployed in a variety of applications and environments, including for example, search and rescue, military operations, and industrial operations. Unmanned robotic vehicles can help to avoid the need to expose humans to hazardous environments, such as unstable buildings, military conflict situations, and chemically, biologically, or nuclear contaminated environments.
Unmanned robotic vehicles face many challenges when attempting mobility. Terrain can vary widely, including for example, bumpy or smooth surfaces, firm or soft ground, loose and shifting materials, etc. For small robotic vehicles, the challenges become even greater. A vehicle optimized for operation in one environment may perform poorly in other environments.
The use of endless tracks are known to provide a good compromise which allows a robotic vehicle to accommodate a large variation in terrain types while maintaining relatively good traction and maneuverability. For example, tank-like vehicles using a pair of parallel endless tracks can provide high stability in some environments.
Tracked vehicles are typically steered using skid steering. In skid steering, the tracks on opposite sides of the vehicle are moved at different rates. Skid steering can be inefficient, as portions of the tracks move perpendicular to the direction of travel. There can be significant friction opposing this sideways motion. For longer tracks, greater force must be applied to overcome this friction. The inefficiency of skid steering also increases for tighter radius turns. The inefficiency of skid steering is at a peak when there is no net forward movement of the vehicle, only rotation around a central pivot point. A sharp turning radius can also result in significant stress on the vehicle suspension components due to the lateral movement. For lightweight robotic vehicles which tend to have limited drive power available, sharp turns may therefore be difficult or impossible to obtain.